1. Field of the Invention
The present invention relates to fluorinated poly(arylene ether) compositions for use in coating microelectronic structures, such as integrated circuits, and the method for their manufacture. More particularly, this invention relates to the use of novel bisphenol reactants in the method of manufacturing novel poly(arylene ether) compositions which possess improved properties such as higher glass transition temperature and lower dielectric constant.
2. Background of the Invention
Fluorinated poly(arylene ethers) based upon decafluorobiphenyl have been used extensively as replacements for polyimides for use in spin-coating substrates, such as multichip modules, printed circuit boards, integrated circuits and other microelectronic devices in intermetal dielectric production. These fluorinated poly(arylene ethers), which are commercially available from AlliedSignal Inc. under the tradename "FLARE.TM.", not only exhibit a thermal stability comparable to that of polyimides but also possess about ten to forty times lower moisture absorption rate, a dielectric constant in the range of about 2.35 to about 2.65, and good retention of storage modulus above their glass transition temperature ("Tg"). These properties are relevant not only to enhanced circuit performance, i.e. higher speed, lower power consumption, and reduced signal-to-noise ratios, but also to lower processing costs. By highly cross-linking these compounds with cross-linking agents or cross-linkable pendent groups, their performance may be enhanced under process integration conditions, i.e. a Tg increase to greater than about 300.degree. C. See Lau, A. N. K., et al., Am. Chem. Soc., Polymer Preprints, 33(1), 996-997 (1992).
Also well-known in the art are methods for synthesizing ethynylated biphenyl monomers such as 2,2'-bis(phenylethynyl)-5,5'-diaminobiphenyl by first producing 2,2'-diiodo-5,5'dimethoxybiphenyl from 3,3'-dimethoxybiphenyl. See Lindley, P. M., et al., in J. Polym. Sci., Part A: Polym. Chem., 1061-1071 (1991) and U.S. Pat. No. 4,683,340 to Lindley, et al. together hereinafter referred to as "Lindley"!. However, the yield of ethylnylated aromatic compounds produced therefrom is very low, i.e. 4% to 14%.
It is further well known in the art to incorporate such ethynylated biphenyl monomers such as 2,2'-bis(phenylethynyl)-5,5'diaminobiphenyl and 2,2'-bis(phenylethynyl)-5,5'-diaminobenzidine in the synthesis of high-temperature resistant, high-performance polyphenylquinoxalines and polybenzimidazoles. However, such methods are also laborious, costly, and low-yielding. See Lau, K. S. Y., "Chemistry, Characterization, and Processing of IMC Curing Polymers," Final Report, Air Force Contract F33615-79-C-5101, for period of September, 1979 to June, 1983, Hughes Aircraft Company (1983).
It would be desirable to provide an improved fluorinated poly(arylene ether) composition which would possess a Tg in excess of about 300.degree. C. without having to highly cross-link the compound or include cross-linkable pendent groups as well as without sacrificing any of the other properties associated with known fluorinated poly(arylene ether) compounds. It would also be desirable to provide an economical, high-yielding process for producing such compositions.